Oil is necessary for lubrication and cooling of an internal combustion engine. Because lubricating oil flows to all parts of the engine, it is desirable that it does not carry abrasive or corrosive material. Such material may come from the combustion process, dirt in inducted air, or from parts of the engine itself. Therefore, it is common practice to filter oil or parts of the oil as it flows through the system to reduce wear of an oil filter.
Ideally, oil filters remove all abrasive materials and particles in the oil, even microscopic metal particles which are abraded from the moving surfaces of the engine during normal engine operation. However, for a filter to remove all of this material, the filter would have to be designed and constructed of a material suitable to remove these microscopic particles. As a result, such a filter would either severely impede the flow of oil to a degree where insufficient oil would flow or excessively high oil pressures would be required to force oil through this filter.
Currently, one proposed solution to filter out ferrous particles includes modifying oil filters after manufacture with a reusable magnetic core insert, as described in U.S. Pat. No. 5,228,990, issued to Chiang. Such inserts are intended to be inserted into the core of an oil filter before the oil filter is attached to an engine. In particular, the metallic insert is a cylindrical-shaped structure that includes a plurality of alternating layers of washers, cylindrical sieves and magnets. The layers are stacked one upon each other to form the cylindrical core. The core is sealed at both ends by caps. The core also includes a centrally located cylindrical sieve extending between the end caps. During operation of the motor, oil is circulated through the oil filter, such that any ferrous particles are drawn from the oil by the magnets of the core insert. Although such core inserts are effective at filtering out ferrous materials, they are not without their problems.
First, because such core inserts are manufactured from repeating layers of metal and magnets, they are expensive. Also, because only a small portion of the length of the insert is magnetized, the effectiveness of the inserts to filter out ferrous particles is limited.
Thus, there exists a need for an improved oil filter having a metallic filter that not only captures a large percentage of ferrous particles, but also is economical to manufacture and meets the performance expectations of the operator of the vehicle.